Cutting rotor assembly

ABSTRACT

A cutting rotor of the general type commonly used in wood working planers and jointers has blades secured in slots in a hub by clamping screws that at least partially intersect the blades, and also generate a clamping pressure on the side of the blade nearest the axis of rotation of the rotor. The center of gravity of the screws is disposed with respect to the axis of rotation so that movement of the screws induced by running vibrations and centrifugal force will tend to increase the clamping pressure. The screws are accessible for adjustment on the exterior of the assembly via openings in the hub and blades.

United States Patent Morse CUTTING ROTOR ASSEMBLY PrimaryExaminer-Andrew R. Juhasz [76] Inventor: Glenn B. Morse, 321 FountainSt.

NE APL No 1 Grand Rapids Assistant Exammer-W. D. Bray Mich 49502Attorney, Agent, or FirmGlenn B. Morse [22] Filed: Aug. 29, 1973 57ABSTRACT [21] Appl. No.: 392,781 A cutting rotor of the general typecommonly used in wood working planers and jointers has blades secured[52] us Cl 144/230 29/105 144/117 in slots in a hub by clamping screwsthat at least par- I' /218 541/292 tially intersect the blades, and alsogenerate a clamp- [51] Int CL i 13/64 ing pressure on the side of theblade nearest the axis [58] Field 241 172 of rotation of the rotor. Thecenter of gravity of the R l SCI'CWS is disposed respect to the axis Ofrotation so that movement of the screws induced by running [56]References Cited vibrations and centrifugal force will tend to increasethe clamping pressure. The screws are accessible for 9 fl PATENTSadjustment on the exterior of the assembly via open- 5 3,500 Ti ison144/230 h h b db] d 1,620,847 3/1927 Whisler 144/230 mgs m e u an 3 es2,997,082 8/1961 Schubert et al 144/230 6 Claims, 9 Drawing FiguresCUTTING ROTOR ASSEMBL BACKGROUND OF THE INVENTION The cutting action ofplaners and jointers commonly used in wood working operations is basedupon a rotor assembly which includes a generally cylindrical hub havingslots extending parallel to the axis of rotation, and disposedtangentially with respect to a cylinder somewhat less in diameter thanthat of the cylindrical periphery of the hub. The blades extend tosharpened edges projecting from the hub periphery, and these blades arenormally clamped securely in position such that all of the bladesoperate on the same circumscribed cylindrical surface.

These rotor assemblies rotate at very high speed, and it is obvious thatthe clamping of the blades in position is vital both to the properoperation of the machine, and to assure the safety of the operator. Theclamping action must be secure enough to resist the action ofcentrifugal force, running vibrations, and the shock forces inevitablyresulting from contact of the blade with hard portions of the wood, orforeign material that may be embedded in it. With regard to the actionof centrifugal force, it should be noted that the position of the centerof gravity of the blades within the slots is such that centrifugal forcewill establish a very strong tendency for the blades to move towardemergence from the slots. Previous systems for securing a blade inposition have included clamping screws in threaded engagement with theportion of the hub radially outward from the blade slots, and whichgenerate an inward clamping pressure against the blades. Thearrangements also include some rather complex wedging systems, in whichthe blade slots are of a width considerably greater than that of theblade, and taper to an increased width toward the central portion of thehub. Wedge assemblies bearing against the radially inner face of theblades are set firmly in position, and any tendency for the blades tomove outward from the slots will correspondingly tend to drag the wedgeunits into tighter clamping because of the convergence of the bladeslots. These wedge units have occasionally included blocks bearingagainst one wall of the blade slots, together with screws in threadedengagement with the blocks, with the heads of these screws bearingdirectly against the inner face of the blades. Adjustment of the bladesto the proper cutting position is difficult in both types of locking,and any looseness of any of this clamping equipment produces an extremedanger, as well as improper cutting action. It is the primary purpose ofthe present invention to provide a locking system of the blades which isreadily adjustable and will maintain the safety of the machine evenunder improper adjustment of the clamping system.

SUMMARY OF THE INVENTION The hub of a rotor embodying the presentinvention is provided with slots of a width slightly in excess of bladethickness, and arranged tangentially with respect to a cylinder of lessdiameter than that of the cylindrical periphery of the hub. These slotscan be traversed by locking screws that have a head portion of adiameter adapted to closely interengage with openings in the blades.This portion extends from the end of the screw to a shoulder which has adiameter larger than that of the blade opening. A bore of sufficientdiameter to receive the shoulder portion of the screw extends from theperiphery of the rotor on an axis preferably perpendicular to the bladeslot to a position such that the screw can be run inward to the pointwhere its head will completely clear the blade slot. This bore obviouslyintersects the blade slot. Extending inward from this bore is a coaxialthreaded bore which is in threaded engagement with the screw.

Blades are inserted into the slots with the screws run into a positionin which they do not obstruct the slots. When the blades are inposition, the screws are backrotated to the point that theend'extremities of the screws become interengaged with the openings inthe blades. At this point, prior to the further tightening of thescrews, the blades are securely interlocked with the hub so that theycannot be thrown out. In one form of the invention, openings in theblades are circular, and fit closely with the intersecting head portionsof the screws so that the screws function as a locating system forautomatic placement of the blades in cutting position. In another formof the invention, the openings in the blades are elongated to permitadjustment of the blades to greater or less extension from the bladeslot. This adjustment is made through access openings intersecting theinner extremities of the slot, so that the screw driver can be insertedat this point and bear on the inner edge of the blades to extend itas'desired'by rotation of the screw driver. The locking screws arepreferably of a form similar to that associated with the so-called Allenrecessed-head cap screws. This arrangement is preferable to the use of ascrew driver slot, as the operating tool is kept out of contact with theopening in the blade, and thus preserves the close fit preferable atthis point.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective elevation of amachine adapted for placement in a position for carrying and driving asmall jointer.

FIG. 2 is a view of an enlarged scale over that of FIG. 1, illustratingthe placement of a small jointer on the table of the machine shown inFIG. 1, with that machine swung to a position in which the column ishorizontal.

FIG. 3 is a side elevation on an enlarged scale of the rotor assemblyused in the machine illustrated in 'FIG. 2.

FIG. 4 is a plan view of an adjustable blade useable in conjunction withthe assembly.

FIG. 5 is a plan view of a fixed-position blade-useable with the rotorassembly.

FIG. 6 is an elevation showing the locking screw.

FIG. 7 is a section on an enlarged scale on aplane normal to the axis ofrotation of the rotor at the locking screws.

FIG. 8 is a section on an enlarged scale of the rotor on a plane normalto the axis of rotation, taken at one of the adjustment axis openings.

FIG. 9 is a section similar to FIG. 7, but showing the blades andlocking system as they are being installed or removed from the hub.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The small jointer indicatedgenerally at 10 in FIG. .2 is designed to be mounted on and driven bythe machine illustrated in FIG. 1. This machine has the base 11supporting a fixed column 12 having a pivot member 13 secured to itsupper extremity. This member rotatably supports a shaft assembly 14fixed with respect to the clamp 15 embracing the moveable column 16carrying the powerhead 17. This powerhead can be identical to that of astandard light-duty drill press. A table 18 has an extension at 19 atthe rear of its underside, and the table unit is adjustably secured tothe bracket 20 for movement about an axis perpendicular to that of thecolumn 16. A clamping bolt 21 constricts the bracket about the column 16to secure the table assembly in position, and a similar clamping bolt 22constricts the clamp 15 about the column 16 to hold the position of thepowerhead and the column with respect to the base assembly.

The jointer 10 shown in FIG. 2 is supported on the table 18, with themachine shown in FIG. 1 placed in a position in which the column 16 ishorizontal by rotation about the axis of the shaft assembly 14. In thisposition, a short shaft (not shown) is carried by the chuck 23 of thepowerhead, and the sheave 24 is carried on this shaft to drive a jointersheave 25 with the belt 26. Tightening and loosening of the belt 26 isaccomplished by relative angular displacement of the bracket 20 withrespect to the powerhead 17 about the axis of the column 16.

The jointer sheave 25 is carried by the shaft 27, which is an extensionof the hub 28 of the cutting rotor. This rotor operates in a recessintersected by the planes of the table sections 29 and 30, which receivethe work pieces. As viewed in FIG. 2, these pieces are placed on thesurface 29, and moved to the left across the surface 30. Normally, thesurface 30 will be slightly above the level of the surface 29 by anamount substantially equal to the thickness of the cut being taken bythe machine. The guard 31 pivots in a horizontal plane about the axis ofthe pin 32 as the workpiece moves across the area occupied by the rotor.A fence 33 provides a lateral positioning stop, and also establishes a90 orientation with respect to the surfaces 29 and 30. As thus fardescribed, the jointer 10 is of conventional construction.

The rotor assembly shown in FIG. 3 is supported at the right end by abearing (not shown) fixed with respect to the base 34 of the jointer 10,and at the left end by the removeable bearing block 35 attached normallyto the base 34. The bearing block receives the shaft extension 27, withthe fixed bearing in the frame supporting the short journal 36.

A group of three removeable blades is secured to the hub 28 by threeclamping screws of the type shown in FIG. 6 for each blade. In theillustrated modification, three blades are installed in the rotor atthree equally angularly spaced positions about the axis of the shaftsections 27 and 36. The system for securing each of the three blades isidentical, and only one of these will be described in detail. Referringto FIG. 8, the rotor 28 is provided with slots 37 parallel to the axisof rotation of the rotor, and it is preferable to provide a cut-awayarea as indicated at 38 ahead of each blade slot, with respect to thedirection of rotation of the rotor, to provide chip clearance. The widthof the slot 37 is preferably a few thousandths of an inch greater thanthe thickness of the blades 39, with the end of the slot being definedby the surface 40. Holes 41 and 42 intersect the slot 37 at a pointopposite the surface to provide access to the back edge of the blades 39for purposes of adjustment. A screw driver can be inserted in the holes41 and 42, and rotated to generate a force between the blades and thehub to project blades to a larger diameter.

Referring to FIG. 9, the insertion of the blades into position in thehub is accomplished by running the screws 43 into a position such thatthey do not obstruct the slots 37. These screws are each received inbores 44 a-c, which are very slightly larger in diameter than thediameter of the shoulder 45 of the screws. These bores intersect theslots 37, and extend far enough beyond the slots so that the entirety ofthe heads of the bolts 43 can be placed beyond a position obstructingthe slots. The threaded portions 46 of the screws 43 are in threadedengagement with the hub 28 at 44d, and the screws are manipulatedpreferably through interengagement of a conventional Allen wrenchinterengaged with the hexagonal recess 47 of the screws. The blades 39have elongated holes 48-50 slightly larger in width than the diameter ofthe cylindrical end portion 51 of the screws 43. The diameter of theshoulder 45 is considerably greater than the width of the elongatedholes 48-50. With the blades 39 inserted in the relationship shown inFIG. 9, a blade position is finally reached in which the screws 43become accessible through the holes 48-50 in the blades, and the screwsmay than be back-rotated to the point that the end portions 51 intersectthe holes 48-50. It is obvious that the blades are now locked to thehub, even prior to the generation of any clamping action.

The degree of extension of the blades 39 so that cutting edges 52operate on the desired circumscribed cylindrical surface is nowaccomplished by a combination of pushing the blades inwardly, andextending them by manipulation through the access openings 41 and 42.When the blades have been placed in their proper position, furtherback-rotation of the screws 43 will establish a clamping action againstthe underside of the blades (with respect to the axis of rotation) whichcan be sufficiently intense to assure the maintanence of the adjustedposition of the blades. The insertion and final adjustment of the bladeswill normally be dome one at a time, and the completion of thisprocedure produces the relationship shown in FIG. 7. In the modificationshown in FIG. 5, the blade 53 has cylindrical openings 54-56 of adiameter slightly in excess of the diameter 51 of the screws 43. In thismodification, the adjustment access openings 41 and 42 would not benecessary, as the blade is oriented completely by interengagement of thescrews with the blades. This form of the invention is particularly welladapted to the use of disposeable blades, which may be of relativelyinexpensive low-carbon steel, supplemented by casehardening. One or twosharpenings of such inexpensive blades can be provided for, after whichthe blades are thrown away. The removal of the need for adjustment makesit easy for the user of the jointer 10 to take the blades out himself,and either sharpen or replace them. Where the blade form shown in FIG. 4is used, it is still possible to make the adjustments with the rotorremaining in operating position in the machine, by placement of areference bar on the table surface 30, and adjusting the blades to thepoint where this bar is barely contacted by the cutting edge 52 of theblades 39. This practice is feasable primarily as a result of the factthat all of the clamping action can be generated by the use of the toolspositioned in a generally radially direction, with the tools extendingout through the operating slot of the machine occupied by the rotor. Theextension of the blades from the slots by the insertion of tools in theopenings 41 and 42 is also done from a generally radial direction.

I claim:

1. A cutting rotor having a central portion provided with at least oneslot, a blade partially received in said slot, and securing meansholding said blade in said slot, wherein the improvement comprises:

means on said central portion defining at least one outer boreintersecting said slot and the surface of said central portion, and athreaded inner bore coaxial with said outer bore; and

screw means constituting said securing means and having a major diameterhead portion selected to fit closely with said outer bore, a threadedportion at one side of said major head diameter portion adapted toengage said threaded inner bore, and a minor diameter head portion onthe opposite side of said major diameter head portion from said threadedportion, said blade having an opening adapted to receive said minordiameter head portion and obstruct said major diameter head portion,said outer bore extending inward beyond said slot by an amount providingfor inward movement of said screw means to a position to admit saidblade into said slot past said minor diameter head portion, said screwmeans having a drive recess in the end thereof adjacent said minordiameter head portion.

2. A rotor as defined in claim 1, wherein said blade opening is circularand adapted to fit closely with said minor diameter head portion.

3. A rotor as defined in claim 1, wherein said blade opening iselongated to receive said minor diameter head portion in variouspositions of extension of said blade from said slot.

4. A rotor as defined in claim 3, additionally including means formingan access aperture intersecting said slot and the surface of saidcentral portion.

5. A rotor as defined in claim 4, wherein said access opening intersectsthe inner extremity of said slot.

6. A rotor as defined in claim 1, wherein said drive recess is isolatedfrom the periphery of said minor diameter head portion.

1. A cutting rotor having a central portion provided with at least oneslot, a blade partially received in said slot, and securing meansholding said blade in said slot, wherein the improvement comprises:means on said central portion defining at least one outer boreintersecting said slot and the surface of said central portion, and athreaded inner bore coaxial with said outer bore; and screw meansconstituting said securing means and having a major diameter headportion selected to fit closely with said outer bore, a threaded portionat one side of said major head diameter portion adapted to engage saidthreaded inner bore, and a minor diameter head portion on the oppositeside of said major diameter head portion from said threaded portion,said blade having an opening adapted to receive said minor diameter headportion and obstruct said major diameter head portion, said outer boreextending inward beyond said slot by an amount providing for iNwardmovement of said screw means to a position to admit said blade into saidslot past said minor diameter head portion, said screw means having adrive recess in the end thereof adjacent said minor diameter headportion.
 2. A rotor as defined in claim 1, wherein said blade opening iscircular and adapted to fit closely with said minor diameter headportion.
 3. A rotor as defined in claim 1, wherein said blade opening iselongated to receive said minor diameter head portion in variouspositions of extension of said blade from said slot.
 4. A rotor asdefined in claim 3, additionally including means forming an accessaperture intersecting said slot and the surface of said central portion.5. A rotor as defined in claim 4, wherein said access opening intersectsthe inner extremity of said slot.
 6. A rotor as defined in claim 1,wherein said drive recess is isolated from the periphery of said minordiameter head portion.